UNIVERSITY PARK, Pa. -- Pennsylvania's forests are fundamentally unhealthy today, according to a forest-management expert in Penn State's College of Agricultural Sciences, who points out that natural regeneration no longer occurs the way it would if the forests were healthy.

"It has gotten to the point where we have to help nature," says Marc McDill, associate professor of forest management, who helps guide forest management practices employed by the state Department of Conservation and Natural Resources, Bureau of Forestry. "The most important reason is that we have too many deer. The simplest explanation is that many natural predators of deer, such as mountain lions and wolves, have been eliminated from Pennsylvania. The only one left is man, and we may not be harvesting enough deer to keep the forest ecosystem in balance."

McDill, who developed forest-management models now used by the Bureau of Forestry to manage the commonwealth's 2.1 million acres of state forests, has been doing research on Pennsylvania forest management for more than five years. The DCNR has provided the university with about $500,000 over that period to fund this research. "The purpose is to provide planning tools to help the Bureau of Forestry achieve its goals more effectively," McDill says. "We developed long-range planning tools to let foresters see how what they do today will impact what the forests look like decades and even a century into the future."

One of the ways state foresters "help" nature is by fencing areas where trees are cut to exclude deer and allow seedlings to survive. About 700 miles of fence already has been erected, according to McDill, and another 700 miles is expected to be built in the next decade or so as more stands of trees are harvested. "Fencing costs $2 a foot, so that's about $7.5 million for fencing alone," he said. "A few years ago, the Legislature passed a law that allowed DCNR to keep 10 percent of the timber receipts to invest in forest regeneration. By necessity, much of that is spent on fencing."

But deer are not the only negative factor affecting forest regeneration, McDill noted. Competing vegetation is also a big problem in some places. DCNR has been applying herbicides to kill hay-scented ferns where they present a problem for seedlings to grow. And where mountain laurel is too thick, they use mechanical cutters to eliminate it.

"Fences are not a magic bullet," says McDill. "First of all, there are places where there aren't that many deer and you don't need a fence. There are some state forests where they may only fence half of their regeneration areas. And there are some areas where they have to fence every regeneration area." McDill points out that it takes seven to 20 years to regenerate a forest tract and that sometimes foresters have to wait as long as seven years until a good crop of tree seeds are produced. So fences are taken down when the regeneration process is complete and they are no longer needed. "But right now, fencing is being put up at a much greater rate than it is being taken down," McDill says. "Ideally, we would like to see some changes to deer-management policies that will reduce the need for fencing."

Besides fencing, the biggest change in Pennsylvania forest management in the last decade or so involves the DCNR switching from "thinning" cuts to "regeneration" cuts, according to McDill. Regeneration cuts, where the majority of the mature trees in a stand are harvested, may be seen by some as clear-cutting, which is not technically accurate because some mature trees (about 15 percent) are left uncut. However, regeneration cuts are important for properly managing forests for a mix of trees of different ages. In thinning cuts, when only a few trees are selected, seedlings often don't survive to replace harvested trees because of deer feeding and inadequate amounts of sunlight reaching the forest floor.

"We shifted the DCNR's management activities away from doing thinning and salvage cuts to regeneration cuts because it really is very important to have young stands as well as old stands in our forests," McDill says. "But too often, when the public hears that we changed from thinning to clear cuts, a lot of people think, 'Wow that is awful -- why are they doing that?' But the goal is to balance the age class distribution of the forests, to have old forest and young stands. The only way to get old forests is to wait -- but plan for areas to become older forests. The only reliable way to get young forests is to cut. It's all part of modern scientific forest management."

A number of factors appear to have conspired to create the problem with regenerating forests in Pennsylvania, McDill concedes, such as high deer populations, invasive plant species, forest fire suppression and perhaps soil acidification from acid rain. "But if you look inside most fenced areas where deer are excluded, it is obvious we are getting acceptable regeneration of desired forest trees such as oak," McDill says. "It's not rocket science and it doesn't take a lot of research to be sure. In the fenced exclusion areas, we are getting regeneration."

###

EDITORS: Contact Marc McDill by phone at 814-865-1602 or e-mail at mmcdill@psu.edu.

Writer/Editor: Jeff Mulhollem Office 814-863-2719 FAX 814-863-9877